Process for multi-coloring metal oxide surfaces



United States Patent 3,258,381 PROCESS FOR MULTl-CULORHNG METAL OXIDE SURFACES Albert E. Howe, New Haven, and Wade Wolfe, Jr., Mount Carmel, Comm, assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia T No Drawing. Filed Aug. 2, 1962, Ser. No. 214,200

Claims. (Cl. 156-249) The present invention relates to a process for coloring metal oxide surfaces and especially multicoloring the surface of anodized aluminum.

Copending application Serial No. 156,483, by Albert E. Howe, filed on December 1, 1961, for Process and Product Formed, the disclosure of which is incorporated herein by reference, teaches an improved process for coloring metal oxide surfaces, especially multicoloring the surface of anodized aluminum and an improved product resulting therefrom. The improved process of copending application Serial No. 156,483 is carried out by providing a decalcomania having coloring agents associated therewith, disposing the decalcomania into intimate contact with the surface of the metal oxide, and treating said surface and applied decalcomania to dispose the coloring agents in said oxide surface and to fix it therein. In a specific embodiment copending application teaches placing a plurality of colors on a transfer surface by placing the colored transfer surface in intimate contact with the surface of a porous metal compound and treating the transfer surface and surface of the metal compound to dispose the color from the transfer surface into the pores of the metal and fix it therein.

Copending application Serial No. 156,483 represents a marked and distinct advance over the art and provides numerous heretofore unobtainable advantages. Among these advantages are: an extremely simple, inexpensive and versatile process; coloring anodized metal surfaces which have not been colored heretofore; and an excellent product having fine color intensities.

The present invention represents a still further improvement over the art. In its broad aspects the process of the present invention relates to a process for applying color or dye to an adhesive transfer medium by placing a coloring agent or plurality of coloring agents on a smooth surface and thereafter bringing the adhesive transfer medium in contact with the colored smooth surface. In its narrower aspects the process of the present invention relates to a process of coloring or dyeingmetal oxide surfaces, especially the surface of anodized aluminum, 0

by transferring color to said metal oxide surface from an adhesive transfer medium having a coloring agent disposed thereon followed by sealing of the color in the metal oxide coating, and the improvement of the present invention resides in applying the coloring agent or plurality of coloring agents to the adhesive transfer medium by placing the coloring agent on a smooth surface and thereafter bringing the adhesive transfer medium in contact with the colored smooth surface.

The process of the present invention provides certain distinct advantages. When the adhesive transfer surface or decal is prepared in volume by standard color printing procedures, each color bearing material may be deposited separately and directly onto the supporting film. These materials are applied in such a manner as to afford a minimum opportunity for the diffusion of one color into another or into the supporting film. In the case of individual or small lot decal preparation the color bearing material may be applied to a supporting film which was already coated with transfer medium. In addition, the

be used are not suspectible to the same close control as a 3,258,381 Patented June 28, 1966 minum.

When the design or color pattern is applied, the colorbearing material is generally in the liquid or semi-liquid form. When the liquid materials are applied to absorptive surfaces, color diffusion will frequently result; however, when the same color bearing surfaces are applied to a non-absorptive surface, such as smooth glass or polished metal, no diffusion can occur.

Another advantage of the present invention is that unwanted diffusion of color is found to be minimized by avoiding wetting absorptive surfaces, which wetting will frequently result in color diffusion. A still further advantage of the present invention is that the color pattern or design need not be applied as an inverted or mirror image as is necessary when the design is applied directly to a decal transfer medium. The use of clear glass for the initial application of the colored design facilitates accurate copying of pictures, legends, and designs and also renders the present process highly advantageous for use on a small scale. Still further, it has been found that the present process achieves an improved decorated product.

The present invention contemplates the application of color or multicolor patterns or designs, to any metal oxide surface. Preferably, a porous anodized aluminum is used. In addition, porous, anodized coatings on aluminum base alloys and other anodizable metals, such as magnesium base alloys may be utilized. Anodic treatment of metals is a conventional procedure in the art and generally longeranodic treatment develops thicker coa-tings and the thicker coatings will accept more intense dye colors; however, as is conventional, the only requirement is that the anodized surface be porous, that is unsealed.

In accordance with the present invention the coloring agent or coloring agents are applied to the smooth surface and preferably permitted to dry. The colors are preferably applied in turn. When completely dried, the adhesive coated transfer medium is applied on top of the colored design. The transfer medium with the adherred colored design is then applied directly to an anodized aluminum surface in accordance with the procedureof copending application Serial No. 158,483 and the colored design is transferred to the aluminum by scaling in boiling water or steam. The smooth surface is preferably pretreated with a release compound which facilitates the removal of the colored design from the smooth surface. Typical release compounds which may be used include, but are not limited to, the following: silicones; chlorofluoro-organic compounds; synthetic and natural waxes; etc. Any smooth surface may be employed in the practice of the present invention. The smooth surface is necessary so that the color or colored design may be readily removed from the smooth surface. It is preferred in the practice of the present invention to employ glass or metal, especially polished metal. The smooth surface should be non-adhesive in order to prevent the color or color pattern from adhering thereto. Typical smooth surface materials which may be employed, include, but are not limited to, glass, polished metals, plastics, lacquered surfaces, glazed ceramics, release treated papers, etc.

After the color pattern or design has been disposed on the adhesive transfer medium the color is transferred to the anodized aluminum surface in the same manner as in copending application Serial No. 156,483. A wide variety of adhesive transfer mediums may be conveniently employed in the practice of the present invention, such as is fully described in the above copending application. After the adhesive transfer surface is coated, the coated material is placed on or brought into intimate contact with the anodized surface. The color is then fixed or sealed into the anodic material in the conventional manner for a sufficient length of time to permit the color to become entirely fixed in the anodic coating. When the fixing operation is by immersion in water or the use of steam, the adhesive and its backing must offer sufficient resistance to separation by water or water vapor that the adhesive will not become separated from the anodized surface before the color is substantially fixed.

The transfer of color from an adhesive transfer medium to an anodic coating is facilitated by the application to theanodic coating of a prewetting material before the application of the adhesive transfer medium to that surface. The prewetting material may be still moist when the transfer medium is applied, or it may have dried to a permanently semi-tacky condition as is typical of pressure sensitive adhesive materials. The prewetting operation accomplishes a more complete wetting of the aluminum oxide surface and assures the necessary intimate contact between the anodic oxide surface and the color bearing material on the transfer meduim.

The transfer of color from an adhesive transfer medium to an anodic coating can also be improved by the use of a dry heating operation before utilization of the hot water or steam sealing procedure. Heating the aluminum with its attached transfer medium decal-at temperatures between 100 and 200 C. for periods of from one to thirty minutes will cause themigration of color into the anodic coating and fixing of the color in that coating. The degree of fixing resulting from this heat treatment is often sufiicient to permit the elimination of the water sealing operation when the decorated aluminum is not to be exposed to the leaching action of an active solvent or other severe deteriorating conditions.

Conventional dyes may be used in the practice of the present invention. In general, numerous dye or coloring agents may be readily employed in the practice of the present invention. Generally the dyes should be water insoluble in order to avoid bleeding of the color and loss of design. Oil soluble dyes have been found quite satisfactory for this purpose. Similarly, conventional carrying mediums compatible with the coloring agents are readily employed. Exemplificative dyes include, but are not limited to the following: Brilliant Oil Blue, BMA,

National Aniline Co.; Oil Brown, y, National Aniline Co.; Oil red, 0, National Aniline Co.; Oracet Blue, B, Ciba Co., Inc.; Orasol Scarlet, 2B, Ciba Co., Inc.; Frobena Yellow, GL, Geigy Co., Inc.; etc. Exemplificative color carrying materials include, but are not limited to, the following: natural rubber water dispersions, natural rubber solvent solution,.styrene-butadiene water dispersions, vinyl acetate resin solutions, acrylic resin solutions, cellulose resin solutions, polyisobutylene resin solutions, etc.

It should be understood that conventional modifications of the foregoing process may be readily practiced, for example, convenitional additives may be utilized to the coloring agent and carrier in order to provide preferred properties. In addition, the colored product may be further treated in accordance with the conventional procedures, if desired.

A wide variety of backing materials, adhesives and solvents for the adhesive and/ or color carriers may be used. Examples of backing materials which may be used, include but. are not limited to, the following: newsprint paper, untreated tracing paper or copying sheets, Mylar film of less than .001 inch thick, special treated paper or plastic film, aluminum foil, etc. Examples of adhesives which may be used include, but are not limited to: vinyl strip coat No. T81TF3, Sherwin Williams Co.; P and S super bond rubber cement, Pierce and Stevens Co.; Dri- Tac pressure sensitive adhesive, Adhesive Products Corporation, etc. Examples of solvents for adhesives and/ or color carriers include the following illustrative solvents: benzene, cyclohexanone, methyl isobutyl ketone, toluene, etc.

Although particularly suitable for small scale operations, this invention offers advantages to large scale, continuous transferring of color whereby conventional printing equipment can be used to impart an uninverted design composed of several colors onto the smooth surface of a continuous belt of polished metal or of plastic. Repetitive designs placed onto the smooth surface in this fashion can be continuously removed by bringing into contact with the smooth surface an adhesive transfer .medium in the form of a long or continuous strip. Trans- Example 1 In accordance with the process of the present invention a multicolored design pattern Was applied to clear glass. The picture was copied from a picture placed below the glass. The color bearing material was a vinyl strip coat vehicle thinned with cyclohexanone and containing dye color. The color pattern was applied with a small camel hair brush and the glass had been pre-treated with a silicone solution to improve its reease properties.

After the design was applied it was permitted to dry thoroughly and then was removed from the glass by placing the adhesive surface of a pressure-sensitive decal transfer film directly on the colored design. This was accomplished by employing a sheet of pressure sensitive film which was lightly coated on the adhesive with an undiluted rubber cement. As soon as the rubber had dried to a tacky surface it was pressurized down onto the top surface of the design and rolled with a rubber roller. The adhesive film was then removed from the glass sun face taking the colored design with it. There was thus obtained in the transfer film a colored design in inverted mirror image. This had been accomplished without any Wetting or heating which would cause unwanted color diffusion.

A piece of 30-minute anodized, unsealed aluminum was coated with a dilute solution of the previously used rubber cement. While this coating was still moist the adhesive fihn bearing the colored design was placed against the treated surface of the anodized aluminum. The adhesive film on the aluminum surface was then rolled with a rubber roller in order to bring the two surfaces into intimate contact. The assembly was then suspended in live, low pressure steam for a period of 25 minutes. On removal from the steam chamber the adhesive film and residues of the colored design previously on the glass transferred with excellent detail into the anodized al'uminum surface.

Example 2 'the same Dri-Tac adhesive and permitted to dry. The

coated sheet, adhesive side down, was then placed on the top surface of the colored design and rolled with a hand roller. After allowing a few minutes for the two Dri-Tac surfaces to thoroughly bond, the paper sheet was peeled away from the Teflon surface, taking the colored design with it A thin coating of Dri-Tac adhesive was applied to the surface of a piece of 30-minute anodized, unsealed aluminum and permitted to dry. The design bearing surface of the typewriter paper decal was then placed in contact with the pretreated surface of the aluminum, and rolled with a hand roller to establish intimate contact. After the decal was firmly adhered to the anodized aluminum, surface, the piece of aluminum with the attached decal was placed in an oven at 100 C. for 30 minutes. The aluminum and decal were then immersed in boiling Water for another 30 minutes. At the expiration of this time, the aluminum piece was removed and dried and the residues of the decal were removed by washing in acetone. The colored design Was found to have transferred in true image and in good definition into the anodic layer on the aluminum.

Example 3 A colored design was applied to the surface of a sheet of release coated paper. The design colors were applied with a spray gun through various shaped stencils. The color vehicles comprised a solvent-thinned rubber cement in which different oil soluble dyes had been dissolved. Each color was separately applied to the release paper surface and permitted to dry befor the application of another color. After the design colors had dried to a tacky state, a sheet of untreated, second-sheet typewriter paper was placed on the colored design and thoroughly rolled with a hand roller. The typewriter paper was allowed to remain in position for a few minutes to establish a bond between it and the color vehicles. It was then peeled away from the release paper, taking the colored design with it. A decal had thus been produced with the design in reverse, or mirror image.

The typewriter paper decal was placed, design side down, on the surface of a piece of 30-minute anodized,

unsealed aluminum. An ordinary household iron with its temperature setting at approximately 193 C., was then placed on the decal which had been adhered to the aluminum. The iron was allowed to remain in position for five minutes and the piece of aluminum then permitted to cool. The residues of the decal were removed by scrubbing with steel wool and a mild scouring powder. The aluminum was not sealed in boiling water or steam as the heat had fixed the color in the aluminum oxide against removal except by a dye solvent or other severe treatment. The transferred design had good color intensity and design definition.

This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects i1- lustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

What is claimed is:

1. A process for multicoloring an adhesive transfer medium which comprises: placing the coloring agents on a smooth non adherent surface, thereafter bringing the adhesive transfer medium into contact with the colored smooth surface and removing said transfer medium from said smooth surface, thereby disposing said coloring agents on said transfer medium while leaving said smooth surface intact.

2. A process according to claim 1 wherein said smooth surface is glass.

3. A process according to claim 1 wherein said smooth surface is a polished metal.

4. A process for multicoloring an adhesive transfer medium which comprises: placing the coloring agents on 7 glass, drying the colored glass, bringing the adhesive transfer medium into contact with the dried, colored glass and removing said transfer medium from the glass, thereby disposing said coloring agents on said transfer medium while leaving said glass intact.

5. In the process of multicoloring metal oxide surfaces by transferring color to the metal oxide surface from an adhesive transfer medium having coloring agents disposed thereon followed by sealing of the color in the metal oxide coating, the improvement of applying the coloring agents to the adhesive transfer medium by placing the coloring agents on a smooth non adherent surface, thereafter bringing the adhesive transfer medium into contact with the colored smooth surface and removing said transfer medium from said smooth surface, thereby disposing said coloring agents on said transfer medium While leaving said smooth surface intact.

6. A process according to claim 5 wherein the colored smooth surface is dried after the coloring agent is applied thereon.

7. A process according to claim 5 wherein the smooth surface is pre-treated with a release compound prior to placing the coloring agent thereon.

8. In the process of multicoloring anodized aluminum by transferring color to the anodized aluminum from an adhesive transfer medium having the color disposed thereon followed by sealing of the color in the aluminum oxide coating, the improvement of applying coloring agents to said adhesive transfer medium by placing the coloring agents on a smooth non adherent surface, thereafter bringing the adhesive transfer medium into contact with the multicolored smooth surface and removing said transfer medium from said smooth surface, thereby disposing said coloring agents on said transfer medium while leaving said smooth surface intact.

9. A process according to claim 8 wherein said smooth surface is glass.

10. A process according to claim 8 wherein the smooth surface is a polished metal.

References Cited by the Examiner UNITED STATES PATENTS 1/1958 Munro 156-240 9/ 1962 MacKenzie 15 6240 

1. A PROCESS FOR MULTICOLORING AN ADHESIVE TRANSFER MEDIUM WHICH COMPRISES: PLACING THE COLORING AGENTS ON A SMOOTH NON ADHERENT SURFACE, THEREAFTER BRINGING THE ADHESIVE TRANSFER MEDIUM TO CONTACT WITH THE COLORED SMOOTH SUFACE AND REMOVING SAID TRANSFER MEDIUM FROM SAID SMOOTH SURFACE, THEREBY DISPOSING SAID COLORING AGENTS ON SAID TRANSFER MEDIUM WHILE LEAVING SAID SMOOTH SURACE INTACT. 